This invention relates to a vehicle body structure which absorbs an impact force exerted when vehicles collide in driving directions, and which cushions the impact force imposed on a passenger compartment. The vehicle body structure is preferred for use in a vehicle having a passenger compartment, or an automobile having a driver seat.
Various track type medium duty traffic systems called new traffic systems are new technologies which generally combine railway technologies on, for example, electric motors, power collection, and vehicle bodies, with automobile technologies concerned with driving of rubber wheels, and which further incorporate computerized control. A technique, called a rubber-tired new traffic vehicle, uses steerable rubber running wheels mounted on a box-shaped vehicle body, makes these running wheels drivable, by an electric motor, and involves dedicated tracks and electric-car lines. Thus, the vehicle can travel along the tracks by the running wheels rotationally driven by the electric motor, while the electric motor is receiving supply of an electric power from power collectors in a travel zone.
An operation management system for the rubber-tired new traffic vehicles links automatic vehicle driving equipment, signal protection devices, communication equipment, power equipment, and disaster protection management facilities to perform centralized management of vehicle schedule control, route control, display control, and operation control, thereby operating vehicles smoothly and safely in an unmanned manner.
With the rubber-tired new traffic vehicle, when control instruments in the operation management system fail, various manual operations and manipulations by the driver are possible. In this case, the travel speed is limited to a low speed. In the case of such a manual vehicle operation or manipulation by the driver, a collision accident to vehicles may occur owing to an erroneous operation or the like. Thus, crush zones for cushioning shock in the vehicle collision are provided at a front end portion and a rear end portion of the vehicle.
FIG. 20 schematically shows the skeletal structure of a vehicle front end portion representing a conventional vehicle body structure. As shown in FIG. 20, an underframe 102 is formed as a continuation of a vehicle body floor (passenger compartment) 101, and a bumper 103 of a U-shape in a plan view is fixed to a front portion of the underframe 102. On the other hand, a front end roof frame 105 of a U-shape in plan view is fixed as a continuation of a vehicle body roof 104, and the front end roof frame 105 and the bumper 103 are connected together by a plurality of front beams 106 and side beams 107. The front beams 106 and the side beams 107 are connected by connecting beams 108. In this manner, a front gable portion 109 is composed of the underframe 102, bumper 103, front end roof frame 105, and beams 106, 107 and 108. An outer wall 111 of FRP is attached to the outside of the structure thus formed from the skeleton.
Hence, when rubber-tired new traffic vehicles collide head-on, their front end portions contact, and then the respective members are buckled, whereby the front gable portion 109 is crushed, and a cushioning member 110 is also buckled. Thus, the front gable portion 109 and the cushioning member 110 absorb shock due to the collision, whereupon an impact force transmitted to the passenger compartment located behind the front gable portion 109 is relieved, so that deformation of the passenger compartment can be prevented.
The aforementioned vehicle running on the dedicated tracks is preferably streamlined in consideration of the vehicle body""s design and air resistance, and the conventional vehicle body has an acute-angled front end portion. If the front end portion of the vehicle body is in an acute-angled shape, however, head-on collision of the vehicles results in one of the vehicles passing over the other vehicle, and the front gable portion 109 or cushioning member 110 is not properly crushed. Thus, the impact force at the time of collision cannot be absorbed by the front gable portion 109, and the impact force may be partly transferred to the passenger compartment to cause its deformation.
In this case, it is conceivable to mount a bumper protruding to the front of the vehicle body as in an automobile so that in the head-on collision of the vehicles, their vehicle bodies are not displaced, one on top of the other, but their front gable portions 109 are properly crushed. Mounting of a large bumper at the front end portion of the vehicle body leads to a change in the design of the vehicle, markedly deteriorating the appearance quality.
Moreover, since control instruments are installed in the aforementioned front gable portion 109, the cushioning member 110 for absorbing an impact force during collision has to be disposed below the underframe 102. Therefore, when a collision force is inputted to the front end portion of the vehicle, as shown in FIG. 21(a), the front beam 106 is crushed rearward, as shown in FIG. 21(b). Thus, the underframe 102 (the front and rear beams, floor board, etc.), to which a lower part of the front beam 106 has been firmly connected, is deformed in a downwardly bending manner. As a result, the downwardly bent, deformed underframe 102 presses the cushioning member 110 downward to bend it down. Consequently, the cushioning member 110 is further bent, without being buckled in response to an impact force subsequently inputted from the front end portion, and is no more capable of absorbing the impact force sufficiently.
In this case as well, the front end portion of the cushioning member 110 may be configured to protrude forwardly of the vehicle body in order to absorb an impact force, which occurs at head-on collision of vehicles, reliably by the cushioning member 110 by directly inputting the impact force to the front end portion of the cushioning member 110 at the collision. Forward extension of the cushioning member 110, however, leads to a change in the design of the vehicle, markedly deteriorating the appearance quality.
Furthermore, the impact force in the collision is absorbed by the crushing of the constituent members of the front gable portion 109 and the buckling of the cushioning member 110. If the vehicles collide straightly, the impact force in the collision can be absorbed reliably. However, if collision occurs when the vehicle runs on a curve, the impact force cannot be absorbed reliably.
In detail, the cushioning member 110 is designed to absorb the impact force reliably, for example, by having holes in a circumferential surface of a tubular body and buckling in a longitudinal direction at the time of collision. When a collision occurs while the vehicle is running on a curve, an impact force acts on the front end portion of the cushioning member 110 from an oblique direction. As a result, the cushioning member 110 is bent and does not buckle in the longitudinal direction. Hence, the function of the cushioning member 110 may fail to be properly performed, and the impact force during the collision cannot be sufficiently absorbed to cause deformation of the passenger compartment.
The present invention is intended to solve the above-described problems. Its object is to provide a vehicle body structure for achieving increased safety by reliably absorbing shock, which occurs when vehicles collide, without aggravating appearance quality or air resistance.
The vehicle body structure of the present invention for attaining the above object is characterized in that a crush zone for absorbing an impact force in a collision is provided on a front head side of a vehicle relative to a passenger compartment, and a straight portion extending along a vertical direction is formed in a front portion of a vertical beam as a constituent member constituting the crush zone.
Thus, the straight portion can be easily formed without an increase in the number of components. Even if there is a vertical displacement in a collision of vehicles, the straight portions collide, and the resulting impact force is transmitted to the crush zone. One of the vehicles does not run onto the other vehicle, but the crush zone is crushed, and can reliably absorb the impact force due to the collision. In this case, a shock absorbing member, such as a bumper, need not be provided in a front portion of the vehicle. Nor is appearance quality or air resistance aggravated. The safety of the vehicle can be increased without fail.
The vehicle body structure of the present invention is also characterized in that the length of the straight portion is set according to the amount of vertical displacement during travel of the vehicle.
Thus, the length of the straight portion can be minimized, and the degree of freedom of vehicle design can be heightened. Consequently, appearance quality can be improved, and air resistance can be decreased to improve fuel economy.
The vehicle body structure of the present invention is also characterized in that the vertical beam connects a roof frame and an underframe, and an inclined portion inclined forwardly is formed in an upper portion of the vertical beam, while the straight portion is formed in a lower portion of the vertical beam.
Thus, an appropriate straight portion is formed, whereby the safety of the vehicle can be increased, without aggravation of the appearance quality or air resistance of the vehicle.
The vehicle body structure of the present invention is also characterized in that a plurality of the vertical beams are provided in the width direction of the vehicle.
Thus, a plurality of straight portions can be provided in the width direction of the vehicle. The straight portions reliably collide with each other, and the resulting impact force can be absorbed by the crush zone without fail.
The vehicle body structure of the present invention is also characterized in that the straight portion is located at the most forward position.
Thus, the straight portions reliably collide with each other, and the resulting impact force is transmitted to the crush zone, and can be absorbed thereby without fail.
The vehicle body structure of the present invention is also characterized in that the vertical beam connects a roof frame and an underframe, a bumper is connected to the underframe, and the bumper has a central portion protruding forwardly of the vehicle and has buckling strength changing means provided in opposite side portions.
Thus, in a collision of the vehicles, the bumper is longitudinally buckled into deformation by the buckling strength changing means, whereby an impact force in the collision can be easily absorbed to increase the safety of the vehicle.
The vehicle body structure of the present invention is also characterized in that the opposite side portions of the bumper are weakened relative to the central portion by the buckling strength changing means.
Thus, in a collision of the vehicles, the central portion of the bumper moves rearward, and the opposite side portions buckle, so that the impact force can be reliably absorbed to increase the safety of the vehicle.
The vehicle body structure of the present invention is also characterized in that the buckling strength changing means is holes formed in the bumper.
Thus, an impact force in a collision can be absorbed by a simple and inexpensive structure.
The vehicle body structure of the present invention is also characterized in that a reinforcing member is provided in the central portion of the bumper.
Thus, when the vehicles collide, the central portion of the bumper reinforced with the reinforcing member recedes without buckling, while the opposite side portions of the bumper buckle, so that the impact force can be absorbed reliably.
The vehicle body structure of the present invention is also characterized in that a cushioning member located behind the constituent member and adapted to buckle by the impact force, thereby relieving the impact force, is provided on one side in the vertical direction of the straight portion, and an auxiliary member is provided for bending the constituent member away from the cushioning member when the impact force is inputted.
Thus, when an impact force in a collision of the vehicles is inputted to the constituent member of the crush zone, the constituent member is bent by the auxiliary member away from the cushioning member. The constituent member does not bend the cushioning member from above, and does not impair the essential function of the cushioning member, the function of absorbing the impact force by its buckling in the longitudinal direction. Since the shock of collision of the vehicles is reliably absorbed, safety can be increased.
The vehicle body structure of the present invention is also characterized in that the constituent member includes a bumper connected to a lower end portion of the vertical beam, and a beam member constructed between the bumper and a vehicle body, and a front portion of the beam member is bent toward the cushioning member to constitute the auxiliary member.
Thus, the auxiliary member can be constituted at a low cost and with ease, without impairment of the function of the beam member constituting the crush zone. At the time of a collision, the beam member is deformed toward the cushioning member, and a loss of the function of the cushioning member due to deformation can be prevented.
The vehicle body structure of the present invention is also characterized in that the constituent member includes a bumper connected to a lower end portion of the vertical beam, a reinforcing member fixed behind the bumper, and a beam member constructed between the bumper and the reinforcing member, and a front portion of the beam member is curved toward the cushioning member to constitute the auxiliary member.
Thus, the auxiliary member can be constituted at a low cost and with ease, without impairment of the function of the beam member constituting the crush zone. At the time of a collision, the beam member is deformed toward the cushioning member, and a loss of the function of the cushioning member due to deformation can be prevented.
The vehicle body structure of the present invention is also characterized in that the constituent member is a bumper connected to a lower end portion of the vertical beam, continued from the straight portion, and inclined rearward, and the bumper covers at least part of the cushioning member.
Thus, the cushioning member is easily disposed without deterioration of appearance quality. Shock in a collision can be reliably absorbed by deformation of the cushioning member.
The vehicle body structure of the present invention is also characterized in that a cushioning member located behind the constituent member and adapted to buckle by the impact force, thereby relieving the impact force, is provided on one side in a vertical direction of the straight portion, and a protrusion for secondary collision, which is exposed forward, is provided in a front end portion of the cushioning member.
Thus, when an impact force in a collision of vehicles is inputted to the crush zone, the constituent member crushed by the impact force presses the cushioning member, trying to deform it into inclination. Before then, however, the protrusions for secondary collision collide with each other. Thus, the inclination of the crash portions is prevented, and the cushioning members are properly buckled in the longitudinal direction by the impact force inputted from ahead, being capable of absorbing the collision force reliably.
The vehicle body structure of the present invention is also characterized in that a plurality of cushioning members for relieving the impact force by being buckled by the impact force are arranged side by side on right and left sides of the vehicle behind the straight portion, and front end portions of the cushioning members are connected by a connecting member.
Thus, the flexural rigidity of each cushioning member is increased. Even when the vehicles collide obliquely and the resulting force acts on the cushioning member obliquely, the cushioning member is not bent, but is buckled longitudinally, becoming capable of absorbing the impact force reliably. The safety in collision can be increased.
The vehicle body structure of the present invention is also characterized in that the cushioning member includes a buckling portion extending forward from a base end portion attached to a vehicle body, and a crash portion attached to a front end portion of the buckling portion, reinforcing means is provided in the mounting area of the vehicle body and the buckling portion, and a reinforcing member is provided in the connecting area of the buckling portion and the crash portion.
Thus, the surface rigidity at the connecting areas of the vehicle body, the buckling portion, and the crash portion is increased. Even when an impact force in a collision acts on the cushioning member obliquely, the cushioning member is not bent, but is buckled longitudinally and can absorb the impact force reliably.
The vehicle body structure of the present invention is also characterized in that a cushioning member for relieving the impact force by being buckled by the impact force is provided behind the straight portion, and a vertical restraining member for inhibiting vertical displacement, relative to a member to be collided with, in the collision is provided in a front end portion of the cushioning member.
Thus, when the front end portion of the cushioning member is struck in a collision of the vehicles, vertical displacement at the crash portion is inhibited by the vertical restraining member. The crash member is properly buckled in the longitudinal direction, and can absorb the impact force reliably. As noted here, shock in the collision can be reliably absorbed to increase safety, without aggravating appearance quality or air resistance.
The vehicle body structure of the present invention is also characterized in that the vertical restraining member is constituted by fixing a plurality of horizontal engagement plates at predetermined intervals in a hollow box attached to the front end portion of the cushioning member.
Thus, when the front end portions of the cushioning members collide with each other, the engagement plates deform the front surfaces of the boxes, and engage each other, thereby inhibiting vertical displacement. The crash members are properly buckled in the longitudinal direction, and thus can absorb the impact force reliably. Furthermore, the vertical restraining member is composed of the plural engagement plates, so that the structure can be simplified and lowered in cost.
The vehicle body structure of the present invention is also characterized in that the plurality of engagement plates are fixed to the rear surface of the hollow box, and predetermined gaps are formed between the front surface of the hollow box and the plurality of engagement plates.
Thus, when the front end portions of the cushioning members collide, the boxes are easily deformed because of the gaps during pushing of the front surfaces of the hollow boxes by the engagement plates. As a result, the engagement plates engage each other, and can inhibit vertical displacement reliably.
The vehicle body structure of the present invention is also characterized in that the vehicle is constituted by mounting a plurality of running wheels to a box-shaped vehicle body having the crush zones provided ahead of and behind the passenger compartment, and the vehicle rotationally drives the running wheels while being supplied with an electric power, whereby the vehicle can travel along dedicated tracks.
Thus, the vehicle body structure of the present invention can be applied to the rubber-tired new traffic vehicle which runs automatically in an unmanned manner on dedicated tracks, and can increase the safety of the vehicle reliably without aggravating appearance quality or air resistance.